Method of forming a composite article

ABSTRACT

A method of forming a composite article including a first portion comprising a cured elastomer and presenting an engagement surface, and a second portion comprising a thermoplastic composition and presenting a locking surface is disclosed. The method comprises the step of forming a plurality of engagement voids in the engagement surface of the first portion. Each engagement void penetrates into the engagement surface of the first portion and is defined by a side wall which forms an acute angle with the engagement surface. The method also includes the step of applying the thermoplastic composition onto the engagement surface of the first portion to form the second portion such that the locking surface abuts the engagement surface and defines a plurality of locking protrusions disposed in the plurality of engagement voids of the first portion.

FIELD OF THE DISCLOSURE

The present disclosure generally relates to a method of forming acomposite article comprising a first and a second portion.

BACKGROUND OF THE DISCLOSURE

Composite articles often include one or more polymeric materials. Insome embodiments, the use of different polymeric materials provides acomposite article with performance properties which cannot be obtainedwith an article comprising a single polymeric material. For example, acomposite article can include an elastomeric material (i.e. a rubber)that provides elasticity, and a thermoplastic which provides rigidity.As another example, a composite article can include an elastomericmaterial which provides elasticity, and a thermoplastic material whichprovides low permeability. As yet another example, a composite articlecan include an elastomeric material which provides elasticity and athermoplastic material which provides low surface energy. Stated simply,composite articles can offer improved performance properties overarticles formed with a single material.

Many composite articles require various layers or portions comprisingdifferent polymeric materials be attached, affixed, adhered, or bondedto one another. In some embodiments, the different polymeric materialscan be mechanically attached to one another (e.g. attached to oneanother with screws). However, when different polymeric materials can bebonded directly to one another (e.g. attached to one another withoutscrews) many advantages can be obtained with the composite articleformed therefrom. For example, bonding materials directly to one anothercan (1) minimize design requirements, (2) reduce weight, (3) reducevibration, (4) provide a seal, and (5) minimize the impact of thermalexpansion.

Polymeric materials can be adhered to one another with an adhesiveand/or thermally bonded (e.g. co-molded together). A primer can be usedto treat the surfaces to be bonded or adhered to one another, or thesurfaces to be bonded or adhered to one another can be pretreated (e.g.with a corona treatment) in an effort to improve the strength of thebond between the different polymeric materials.

However, not all polymeric materials adhere or bond well to one another.Various properties associated with the polymeric materials can provideperformance properties such as elasticity for impact resistance, lowsurface energy for reduced friction, etc. These very properties can makeit difficult to bond different polymeric materials together.

Despite the availability of various adhesives and methods for bondingdifferent polymeric materials together, composite articles can failunder physical and/or environmental (e.g. thermal/high temperature)stress resulting in adhesive failure or delamination of the differentpolymeric materials. As such, there remains a need for improved methodsof bonding different polymeric materials to one another to formcomposite articles.

SUMMARY OF THE DISCLOSURE AND ADVANTAGES

The instant disclosure provides a composite article including a firstportion and a second portion. The first portion comprises a curedelastomer and presents an engagement surface. The engagement surfacedefines a plurality of engagement voids. Each engagement void penetratesinto the engagement surface of the first portion and is defined by aside wall which forms an acute angle with the engagement surface. Thesecond portion comprises a thermoplastic composition and presents alocking surface.

The instant disclosure also provides a method of forming a compositearticle comprising the steps of forming a plurality of engagement voidsin the engagement surface of the first portion, and applying thethermoplastic composition onto the engagement surface of the firstportion to form the second portion such that the locking surface abutsthe engagement surface and defines a plurality of locking protrusionsdisposed in the plurality of engagement voids of the first portion.

The method produces an engagement surface and locking surface which abutto provide a robust bond between the first portion comprising the curedelastomer and the second portion comprising the thermoplasticcomposition. The bond formed is flexible, durable, and resistant tofailure under physical and environmental stress.

BRIEF DESCRIPTION OF THE DRAWINGS

Other advantages of the present invention will be readily appreciated,as the same becomes better understood by reference to the followingdetailed description when considered in connection with the accompanyingdrawings.

FIG. 1 is an enlarged cross-sectional view of a composite articlecomprising a first and a second portion.

FIG. 2 is an isolated, enlarged, cross-sectional view of a first portionof the composite article including an engagement surface which defines aplurality of engagement voids.

FIG. 3 is an isolated, enlarged, cross-sectional view of a compositearticle including a first portion presenting an engagement surface whichdefines a plurality of engagement voids having different cross-sectionalprofiles.

FIG. 4 is a scanning electron microscope image of a surface of a portionwhich does not define a plurality of engagement voids.

FIG. 5 is a scanning electron microscope image of an engagement surfaceof a first portion which defines a plurality of engagement voids.

FIG. 6A is an isolated, enlarged, cross-sectional view of an initialportion comprising uncured elastomer.

FIG. 6B is an isolated, enlarged, cross-sectional view of a plurality ofparticles on a surface of the initial portion of FIG. 6A.

FIG. 6C is an isolated, enlarged, cross-sectional view of the pluralityof particles of FIG. 6B pressed into the surface of the initial portion.

FIG. 6D is an isolated, enlarged, cross-sectional view of a firstportion presenting the engagement surface which defines a plurality ofengagement voids formed via curing the initial portion and dissolvingthe plurality of particles of FIG. 6C.

FIG. 6E shows a composite article comprising the first portion of FIG.6D and a second portion presenting a locking surface which abuts theengagement surface.

FIGS. 1 through 6E are exemplary in nature and are not drawn to scaleand are, thus, not intended to represent the relative sizes of thevarious components of the composite article, e.g. the first portion, thesecond portion, the engagement surface, the engagement voids, etc.

DETAILED DESCRIPTION OF THE DISCLOSURE

Referring to FIG. 1, wherein like numerals indicate corresponding partsthroughout the several views, a composite article is generally shown at10. The composite article 10 includes a first portion 12 and a secondportion 14. The first portion 12 comprises a cured elastomer andpresents an engagement surface 16. The second portion 14 comprises athermoplastic composition and presents a locking surface 18.

FIG. 2 is an isolated, enlarged, cross-sectional view of the firstportion 12 of the composite article 10 including the engagement surface16. The engagement surface 16 defines a plurality of engagement voids20. Each engagement void 20 penetrates into the engagement surface 16 ofthe first portion 12 and is defined by a side wall 22 which forms anacute angle e with the engagement surface 16.

FIG. 3 is an isolated, enlarged, cross-sectional view of the compositearticle 10 including the first portion 12 presenting the engagementsurface 16 showing a plurality of engagement voids 20 having differentcross-sectional profiles. A cross-sectional profile of each engagementvoid can define any suitable configuration, such as a circle, an oval,or any type of ellipse, a closed parabolic shape, a quadrilateral, orany other type of polygon. Each engagement void 20 penetrates into theengagement surface 16 of the first portion 12 and is defined by a sidewall 22 which forms an acute angle e with the engagement surface 16.Various examples of this acute angle e which is formed with theengagement surface 16 are shown in FIG. 3. Notably, embodiments of thecomposite article 10 which do not have engagement voids 20 that form anacute angle e with the engagement surface 16 of the first portion 12that are formed with the methods disclosed are contemplated herein. Thatis, embodiments of the composite article 10 having engagement voids 20penetrating into the engagement surface 16 of the first portion 12 anddefined by a side wall 22 which forms an angle e which is right, obtuse,and/or acute, with the engagement surface 16 are also contemplated. Thecross-sectional profile of the plurality of engagement voids 20typically depends on how the voids 20 are formed. For example, if theplurality of engagement voids 20 are formed with a salt, such as NaCl,the plurality of engagement voids 20 typically have a rectangular ortriangular cross-sectional profile. If the plurality of engagement voids20 are formed with a blowing agent, such as azodicarbonamide, theplurality of engagement voids 20 typically have an ovular cross-sectionprofile. The configuration of the plurality of engagement voids 20 canbe random, semi-random, or patterned as desired.

FIG. 3 also shows the second portion 14 presenting the locking surface18 abutting the engagement surface 16 and defining a plurality oflocking protrusions 24 disposed in the plurality of engagement voids 20of the first portion 12.

The composite article 10 can be used in a wide array of commercialproducts. In one embodiment, the composite article 10 is incorporatedinto a wheel assembly comprising a rubber tire tread (e.g. comprisingcured elastomer) and a shear band and spokes (e.g. an elastomeric orthermoplastic polyurethane). It is to be appreciated that the compositearticle 10 of the subject disclosure can also have applications notspecifically set forth herein.

A method of forming a composite article 10 comprising the first and thesecond portions 12, 14 is disclosed. The method includes the steps offorming a plurality of engagement voids 20 in the engagement surface 16of the first portion 12, applying the thermoplastic composition onto theengagement surface 16 of the first portion 12 to form the second portion14 such that the locking surface 18 abuts the engagement surface 16 anddefines the plurality of locking protrusions 24 disposed in theplurality of engagement voids 20 of the first portion 12.

The first portion 12 is formed from an initial portion 26 comprising anelastomeric composition. The elastomeric composition comprises, orconsists essentially of, an elastomer/rubber. Of course, one or moretypes of elastomer may be included in the elastomeric composition. Inmany embodiments, the elastomeric composition comprises an elastomerselected from natural polyisoprene, synthetic polyisoprene,polybutadiene, chloroprene rubber, butyl rubber, halogenated butylrubber, styrene-butadiene rubber (SBR), nitrile rubber, ethylenepropylene rubber, ethylene propylene diene rubber (EPDM),epichlorohydrin rubber, polyacrylic rubber, silicone rubber,fluorosilicone rubber, fluoroelastomers, perfluoroelastomers, polyetherblock amides, chlorosulfonated polyethylene, and ethylene-vinyl acetate.The elastomeric composition may also comprise ingredients such asfillers, plasticizers, curatives, and additives.

Various additives can be included in the elastomeric composition.Suitable additives include, but are not limited to, processingadditives, plasticizers, chain terminators, surface-active agents,adhesion promoters, flame retardants, anti-oxidants, water scavengers,dyes, ultraviolet light stabilizers, fillers, acidifiers, thixotropicagents, curatives/cross-linkers (e.g. sulfur based, or peroxide based),catalysts, blowing agents (as described in detail below), surfactants,and combinations thereof. The additive(s) may be included in any amountas desired by those of skill in the art.

Of course, the elastomeric composition is cured or cures (e.g. via heat,UV, inclusion of a room temperature cure package in the elastomericcomposition, etc.) to form the first portion 12 comprising the curedelastomer. In a preferred embodiment, the elastomeric compositioncomprises ethylene styrene butadiene rubber (i.e. the cured elastomercomprises cured SBR).

In some embodiments, the elastomeric composition has a specific gravityof from about 0.9 to about 2.5, alternatively from about 1.2 to about2.1, alternatively from about 1.5 to about 2.0, g/cm³.

With specific regard to the strength and elasticity, in someembodiments, the elastomeric composition can have a tensile strength at50% elongation of from about 5 to about 50, alternatively from about 8to about 40, alternatively from about 10 to about 30, MPa when tested inaccordance with ISO 527. In some embodiments, the elastomericcomposition can have an elongation at break of greater than about 200,alternatively from about 300 to about 700, alternatively from about 350to about 600, alternatively from about 350 to about 450, % when testedin accordance with ISO 527.

In some embodiments, the step of forming the plurality of engagementvoids 20 comprises the steps of: pressing a plurality of particles 30into a surface 28 of an initial portion 26 comprising uncured elastomer;curing the initial portion 26 to form the first portion 12 comprisingthe cured elastomer with the plurality of particles 30 pressed therein;and dissolving the plurality of particles 30 in a solvent therebyforming the plurality of engagement voids 20 in the first portion 12comprising cured elastomer.

In such embodiments, the plurality of particles 30 can comprise anymaterial that can be dissolved or extracted with a liquid or gassolvent. In many embodiments, the particles 30 have a solubility ofgreater than about 1, alternatively greater than about 3, alternativelygreater than about 6, alternatively greater than 10, g per 100 mL of thesolvent at standard temperature and pressure. In preferred embodiments,the particles 30 comprise a salt selected from the group of nitrates,sulfates, chlorides, bromides, iodides, sodium carbonate, potassiumcarbonate, ammonium carbonate, sodium hydroxide, potassium hydroxide,ammonium hydroxide. In one particular embodiment, the particles 30comprise sodium chloride.

In such embodiments, the plurality of particles 30 have an averagediameter of from about 10 to about 500, alternatively from about 20 toabout 400, alternatively from about 50 to about 300, μm. The particles30 can be of various shapes and sizes. For example, the particles 30 canbe circular, ovular, triangular, rectangular, etc. In some embodiments,one, two, three, or even more size populations of particles 30 can bepressed into the initial portion 26.

The plurality of particles 30 can be pressed into the initial portion 26in various amounts based on the area of the surface 28. In someembodiments, the plurality of particles 30 are used in an amountsufficient to form a first portion 12 which defines from about 10 toabout 450, alternatively from about 10 to about 350, alternatively fromabout 10 to about 250, alternatively from about 10 to about 150,engagement voids 20 per cm² of the engagement surface 16.

The plurality of particles 30 can be pressed into the surface 28 of theinitial portion 26 comprising uncured elastomer with a press, a roller,or by any other effective means. The method can include the step ofheating the particles 30, the press, or the roller to a temperature offrom about 25 to about 350, alternatively from about 50 to about 250,alternatively from about 50 to about 150, ° C. prior to the step ofpressing the plurality of particles 30 into the surface 28 of an initialportion 26. In embodiments where the particles are pre-heated, theelevated temperature of the particles helps cure the side wall 22 of theengagement voids 20 which, in-turn, helps form engagement voids 20 whichmaintain their shape and are resistant to collapse. In variousembodiments, the initial portion 26 comprising uncured elastomer isheated from about 50 to about 150, ° C. prior to the step of pressingthe plurality of particles 30 into the surface 28 of an initial portion26.

Once the plurality of particles 30 is pressed into the surface 28 of theinitial portion 26 comprising uncured elastomer, the initial portion 26is cured to form the first portion 12 comprising the cured elastomerwith the plurality of particles 30 pressed therein. The step of curingcan be conducted via heat and/or ultraviolet radiation. When the initialportion 26 is cured via heat, the initial portion 26 can be cured toform the first portion 12 comprising the cured elastomer with theplurality of particles 30 pressed therein at a temperature of from about50 to about 250, alternatively from about 100 to about 220, ° C., and atime of from about 10 to about 60, alternatively from about 20 to about40, min.

Once cured, the plurality of particles 30 are dissolved in a solventthereby forming the plurality of engagement voids 20 in the firstportion 12 comprising cured elastomer. The solvent can be any liquid orgas that can dissolve or extract the particles 30. To this end, thesolvent is selected in conjunction with the composition of the pluralityof particles 30.

In some embodiments, the solvent is a polar solvent. The solvent havinga dielectric constant of about 15 or greater is considered to be a“polar” solvent for purposes of the subject disclosure. The polarsolvent can be aprotic or protic. Suitable non-limiting polar aproticsolvents for purposes of the subject disclosure include triethylphosphate, tetrahydrofuran, ethyl acetate, acetone, dimethylformamide,acetonitrile, dimethyl sulfoxide, nitromethane, and propylene carbonate.Suitable non-limiting polar aprotic solvents for purposes of the subjectdisclosure include formic acid, n-butanol, isopropanol, n-propanol,ethanol, methanol, acetic acid, and water. In a preferred embodiment,the solvent comprises water.

In some embodiments, the solvent is a non-polar solvent. The solventhaving a dielectric constant of less than 15 is considered to be a“non-polar” solvent for purposes of the subject disclosure. Suitablenon-limiting non-polar solvents for purposes of the subject disclosureinclude pentane, cyclopentane, hexane, cyclohexane, benzene, toluene,1,4-dioxane, chloroform, diethyl ether, and dichloromethane.

FIG. 4 is a scanning electron microscope (“SEM”) image of an engagementsurface 16 which is formed when a plurality of particles 30 (of NaCl)are pressed into the surface 28 of the initial portion 26, the pluralityof particles 30 is dissolved, and then the initial portion 26 is curedto form the first portion 12. In FIG. 4, the engagement voids 20 are notproperly formed because the engagement voids 20 are diminished due tothe viscoelastic flow of the uncured elastomer after the particles 30are dissolved and during curing. In contrast, FIG. 5 is an SEM image ofan engagement surface 16 which is formed when the plurality of particles30 is pressed into the surface 28 of the initial portion 26, the initialportion 26 with the plurality of particles 30 pressed therein is curedto form the first portion 12 comprising the cured elastomer with theplurality of particles 30 pressed therein, and then the plurality ofparticles 30 is dissolved in the solvent to form the plurality ofengagement voids 20 in the first portion 12 comprising cured elastomer.The engagement surface 16 shown in FIG. 5 has a plurality of distinctengagement voids 20 which provide for excellent adhesion with the secondportion 14.

The process of the subject application may also form an engagementsurface 16 which defines a plurality of voids that are different thanthe plurality of engagement voids 20. Each of these different voidsdefines an opening in the engagement surface 16, penetrates into thefirst portion 12, and is defined by a side wall 22 which does not forman acute angle e with the engagement surface 16. In such embodiments,once the thermoplastic is applied, the second portion 14 defines theplurality of locking protrusions 24 disposed in the plurality ofdifferent voids. In other words, the engagement surface 16 can includeadditional voids and surface patterns which are different than theengagement voids 20.

In various embodiments, the method includes the step of pre-treating theengagement surface 16 to improve the wet/out and or adhesion of thesecond portion 14 to the first portion 12. In some embodiments theengagement surface 16 is treated with a corona treatment. In otherembodiments, the engagement surface 16 is treated with chemical primer.

A thermoplastic (e.g. a TPU) is then applied to the engagement surface16 of the first portion 12 (e.g. co-molded with the first portion 12 inan injection molding machine) to form the second portion 14 therebyforming the composite article 10. The engagement surface 16 of the firstportion 12 abuts the locking surface 18 of the second portion 14. Morespecifically, the locking surface 18 of the second portion 14 abuts theengagement surface 16 and defines the plurality of locking protrusions24 disposed in the plurality of engagement voids 20 of the first portion12.

The thermoplastic can be applied on the engagement surface 16 via press,mill, roller, vacuum, co-extrusion, injection molding, and compressionmolding. In a preferred embodiment, the second portion 14 is co-moldedwith the first portion 12. For example, the thermoplastic material isapplied to the engagement surface 16 via injection molding.

More specifically, the second portion 14 comprises a thermoplasticcomposition. The thermoplastic composition comprises, consistsessentially of, or consists of, a thermoplastic (thermoplastic asdescribed herein includes thermoplastic elastomers). Of course, one ormore types of thermoplastic may be included in the thermoplasticcomposition. In many embodiments, the thermoplastic compositioncomprises or consists essentially of a thermoplastic or a thermoplasticelastomer selected from polyethylene, polypropylene, polyamide, orthermoplastic polyurethane. In many embodiments, the thermoplasticcomposition comprises a thermoplastic elastomer selected from styrenicblock copolymers, thermoplastic olefins (e.g. polyolefins), elastomericalloys, thermoplastic polyurethanes, thermoplastic copolyester, andthermoplastic polyamides. In a preferred embodiment, the thermoplasticcomposition comprises thermoplastic polyurethane or TPU. In manyembodiments, the thermoplastic composition also comprises or consistsessentially of a polyolefin, i.e., a polyalkene. In some embodiments,the polyolefin can be selected from polyethylene, polypropylene,polymethylpentene, and polybutene-1. In other embodiments, thepolyolefin can also be selected from polyolefin elastomers such aspolyisobutylene, ethylene propylene rubber, ethylene propylene dienemonomer rubber, and poly vinyl chloride. The thermoplastic compositionmay also comprise ingredients such as fillers, plasticizers, curatives,and additives.

In embodiments where the thermoplastic composition comprises a TPU, thethermoplastic composition may include one or more types of TPU. The TPUtypically comprises the reaction product of a polyol, an isocyanate, anda chain extender. The TPU may comprise the reaction of one or more typesof the polyol with one or more types of the isocyanate. The polyol canbe any polyol known in the art. The polyol includes one or more OHfunctional groups, typically at least two OH functional groups. Invarious embodiments, the polyol is selected from the group of polyetherpolyols, polyester polyols, polyether/ester polyols, silicone polyols,fluorinated polyols, biopolyols, polytetrahydrofuran, and combinationsthereof; however, other polyols may also be employed.

In various embodiments, a polyester polyol is reacted with theisocyanate to form a polyester-based TPU. Of course, variouscombinations of different polyols can be reacted to form thepolyester-based TPU. Suitable polyester polyols may be produced from areaction of a dicarboxylic acid and a glycol having at least one primaryhydroxyl group. Suitable dicarboxylic acids may be selected from, butare not limited to, the group of adipic acid, methyl adipic acid,succinic acid, suberic acid, sebacic acid, oxalic acid, glutaric acid,pimelic acid, azelaic acid, phthalic acid, terephthalic acid,isophthalic acid, and combinations thereof. Glycols that are suitablefor use in producing the polyester polyols may be selected from, but arenot limited to, the group of ethylene glycol, butylene glycol,hexanediol, bis(hydroxymethylcyclohexane), 1,4-butanediol, diethyleneglycol, 2,2-dimethyl propylene glycol, 1,3-propylene glycol, andcombinations thereof.

In various embodiments, a polyether polyol is reacted with theisocyanate to form a polyester-based TPU. Of course, variouscombinations of different polyols can be reacted to form thepolyester-based TPU. In other words, the TPU of this embodiment is apolyether-based TPU comprising the reaction product of a polyetherpolyol and an isocyanate. Suitable polyether polyols may be selectedfrom, but are not limited to, the group of polytetramethylene glycol,polyethylene glycol, polypropylene glycol, and combinations thereof.

In various embodiments, a polytetrahydrofuran (polyTHF) is reacted withthe isocyanate to form the TPU. PolyTHF is synthesized by thepolymerization of tetrahydrofuran. The polyTHF and one or moreadditional polyols can be reacted with the isocyanate to form the TPU.Of course, various combinations of different polyols can be reacted toform the TPU. For example, the polyTHF and a polyether polyol can bereacted to form the TPU. One or more types of the polyTHF can be reactedto form the TPU. The polyTHF is also known in the art aspoly(tetramethylene ether) glycol or poly(tetramethylene oxide) and, insome embodiments, has the following general structure:

wherein n is an integer of from about 1 to about 100, alternatively fromabout 5 to about 75, alternatively from about 5 to about 50,alternatively from about 5 to about 20. Alternatively, in suchembodiments, the polyTHF can have a weight average molecular weight offrom about 225 to about 3000, alternatively from about 225 to about 275,alternatively from about 625 to about 675, alternatively from about 950to about 1050, alternatively from about 1750 to about 1850,alternatively from about 1950 to about 2050, alternatively from about2800 to about 3000, g/mol. In these embodiments, the polyol can have ahydroxyl number of from about 30 to about 1000, alternatively from about498 to about 537.4, alternatively from about 408 to about 498.7,alternatively from about 166.2 to about 179.5, alternatively from about106.9 to about 118.1, alternatively from about 60.6 to about 64.1,alternatively from about 54.7 to about 57.5, alternatively from about34.7 to about 40.1, mg KOH/g.

The isocyanate used to form the TPU may be a polyisocyanate having twoor more functional groups, e.g. two or more NCO functional groups. Invarious embodiments, the isocyanate may include, but is not limited to,monoisocyanates, diisocyanates, polyisocyanates, biurets of isocyanatesand polyisocyanates, isocyanurates of isocyanates and polyisocyanates,isocyanate prepolymers, and combinations thereof. Suitable isocyanatesinclude, but are not limited to, aliphatic and aromatic isocyanates. Invarious embodiments, the isocyanate is selected from the group ofdiphenylmethane diisocyanates (MDIs), polymeric diphenylmethanediisocyanates (pMDIs), toluene diisocyanates (TDIs), hexamethylenediisocyanates (HDIs), isophorone diisocyanates (IPDIs), isocyanateprepolymers, and combinations thereof.

The isocyanate may comprise an isocyanate prepolymer. The isocyanateprepolymer is typically a reaction product of an isocyanate and a polyoland/or a polyamine. The isocyanate used in the prepolymer can be anyisocyanate as described above. The polyol used to form the prepolymer istypically selected from the group of ethylene glycol, diethylene glycol,propylene glycol, dipropylene glycol, butane diol, glycerol,trimethylolpropane, triethanolamine, pentaerythritol, sorbitol,biopolyols, and combinations thereof. The polyamine used to form theprepolymer is typically selected from the group of ethylene diamine,toluene diamine, diaminodiphenylmethane and polymethylene polyphenylenepolyamines, aminoalcohols, and combinations thereof. Examples ofsuitable aminoalcohols include ethanolamine, diethanolamine,triethanolamine, and combinations thereof.

In some embodiments, the isocyanate may comprise an isocyanurated HDI,such as HDI isocyanural. Isocyanurated HDIs, which are typically highlyfunctional low-viscosity isocyanates, react with the bioresin componentto form a coating which has excellent UV, chemical, and solventresistance, has excellent adhesion and durability, and is hard yetflexible. In one such embodiment, the isocyanate has an NCO content offrom about 21.5 to about 22.5 weight percent, a viscosity at 23° C. offrom about 2,500 to about 4,500 mPa·sec, and a percent solids of about100 weight percent.

Specific isocyanates that may be used include, but are not limited to,toluene diisocyanate; 4,4′-diphenylmethane diisocyanate; m-phenylenediisocyanate; 1,5-naphthalene diisocyanate; 4-chloro-1; 3-phenylenediisocyanate; tetram ethylene diisocyanate; hexamethylene diisocyanate;1,4-dicyclohexyl diisocyanate; 1,4-cyclohexyl diisocyanate,2,4,6-toluylene triisocyanate,1,3-diisopropylphenylene-2,4-dissocyanate;1-methyl-3,5-diethylphenylene-2,4-diisocyanate;1,3,5-triethylphenylene-2,4-diisocyanate;1,3,5-triisoproply-phenylene-2,4-diisocyanate;3,3′-diethyl-bisphenyl-4,4′-diisocyanate;3,5,3′,5′-tetraethyl-diphenylmethane-4,4′-diisocyanate;3,5,3′,5′-tetraisopropyldiphenylmethane-4,4′-diisocyanate;1-ethyl-4-ethoxy-phenyl-2,5-diisocyanate; 1,3,5-triethylbenzene-2,4,6-triisocyanate; 1-ethyl-3,5-diisopropylbenzene-2,4,6-triisocyanate, and 1,3,5-triisopropylbenzene-2,4,6-triisocyanate. Other suitable polyamide imide coatings canalso be prepared from aromatic diisocyanates or isocyanates having oneor two aryl, alkyl, arylalkyl or alkoxy substituents wherein at leastone of these substituents has at least two carbon atoms. Of course,various combinations of the isocyanates referenced herein can be used toform the TPU.

The chain extender used to form the TPU may be selected from the groupof, but are not limited to, diols, triols, and tetraols. Suitable diolsinclude, but are not limited to, ethylene glycol, propylene glycol,butylene glycol, 1,4-butanediol (BDO), butenediol, butynediol, xylyleneglycols, amylene glycols, 1,4-phenylene-bis-beta-hydroxy ethyl ether,1,3-phenylene-bis-beta-hydroxy ethyl ether,bis-(hydroxy-methyl-cyclohexane), hexanediol, and thiodiglycol; diaminesincluding ethylene diamine, propylene diamine, butylene diamine,hexamethylene diamine, cyclohexalene diamine, phenylene diamine,tolylene diamine, xylylene diamine, 3,3′-dichlorobenzidine, and3,3′-dinitrobenzidine; alkanol amines including ethanol amine,aminopropyl alcohol, 2,2-dimethyl propanol amine, 3-aminocyclohexylalcohol, and p-aminobenzyl alcohol; and combinations of any of theaforementioned chain extenders. Other suitable chain extenders includeglycerine, trimethylolpropane (TMP), and pentaerythritol.

In some embodiments, the TPU has a glass transition temperature (Tg) offrom about −15 to about −50° C., alternatively from about −30 to about−40, ° C. and/or a Vicat Softening Temperature of greater than about100° C., alternatively of from about 120 to about 160° C. when tested inaccordance with ASTM D 1525.

Suitable TPU's are commercially available from BASF Corporation ofFlorham Park, N.J. under the trade name Elastollan®.

In some embodiments, the thermoplastic composition is relatively lowdensity. That is, in some embodiments, the thermoplastic composition hasa specific gravity of from about 0.8 to about 1.9, alternatively fromabout 0.9 to about 1.60, alternatively from about 1.0 to about 1.3,g/cm³.

In some embodiments, thermoplastic composition has a melt flow rate offrom about 0.5 to about 15, alternatively from about 1 to about 10,alternatively from about 1 to about 5, g/10 minutes when tested inaccordance with ISO 1133 and has a flexural modulus at a roomtemperature of from about 350 to about 700, alternatively from about 450to about 600, alternatively from about 500 to about 550, MPa when testedin accordance with ISO 178.

In some embodiment, with specific regard to the strength and elasticity,the second portion 14 can have a tensile strength at 50% elongation offrom about 5 to about 50, alternatively from about 8 to about 40,alternatively from about 10 to about 30, MPa when tested in accordancewith ISO 527. The second portion 14 can have an elongation at break ofgreater than about 200, alternatively from about 300 to about 700,alternatively from about 350 to about 600, alternatively from about 350to about 450, % when tested in accordance with ISO 527.

In various embodiments, the thermoplastic composition has a Shorehardness of from about 70 Shore A to about 80 Shore D.

In some embodiments, the thermoplastic composition has a Shore hardnessof from about 70 to about 98 Shore A, a tensile strength of about 10 toabout 80 MPa, an elongation at break of about 500 to about 700%, a meltflow rate of about 10 to about 100 g/10 min at 190° C., 22.6 kg. Inother embodiments, the thermoplastic composition has a Shore hardness offrom about 54 to about 80 Shore D, a tensile strength of about 20 toabout 100 MPa, an elongation of about 300%, and a melt flow rate of fromabout 20 to about 200 g/10 min at 220° C., 22.6 kg.

In yet other embodiments, the thermoplastic composition has a Shorehardness of from about 70 to about 90 Shore D, a tensile strength ofabout 20 to about 100 MPa, and an elongation of from about 10 to about50. In such embodiments, the thermoplastic composition could further bedefined as a two-component cast elastomer thermoset (e.g. apolyurethane).

Referring now to FIGS. 6A-E, one embodiment of the subject method isdescribed. FIG. 6A shows the initial portion 26 comprising uncuredelastomer (e.g. comprising an uncured EPDM composition). FIG. 6B showsthe plurality of particles 30 (e.g. NaCl) on a surface 28 of the initialportion 26. FIG. 6C shows the plurality of particles 30 pressed into thesurface 28 of the initial portion 26. After the initial portion 26 withthe plurality of particles 30 pressed therein is cured to form the firstportion 12 comprising the cured elastomer with the plurality ofparticles 30 pressed therein, the plurality of particles 30 is dissolvedin the solvent to form the plurality of engagement voids 20 in the firstportion 12 comprising cured elastomer. That is, the plurality ofengagement voids 20 is formed in the first portion 12 wherein eachengagement void 20 penetrates into the engagement surface 16 of thefirst portion 12. FIG. 6D shows the first portion 12 presenting theengagement surface 16 which defines a plurality of engagement voids 20formed when the particles 30 were dissolved. A thermoplastic (e.g. aTPU) is then applied to the engagement surface 16 of the first portion12 (e.g. co-molded with the first portion 12 in an injection moldingmachine) to form the second portion 14. FIG. 6E shows the compositearticle 10 comprising the first portion 12 and the second portion 14.The first portion 12 comprises the cured elastomer and presents anengagement surface 16. The second portion 14 comprises a thermoplasticcomposition and presents the locking surface 18. The locking surface 18abuts the engagement surface 16 and defines the plurality of lockingprotrusions 24 disposed in the plurality of engagement voids 20 of thefirst portion 12.

In some alternative embodiments, the step of forming the plurality ofengagement voids 20 further comprises the steps of pressing a pluralityof particles 30 into a surface 28 of an initial portion 26 comprisinguncured elastomer, curing the initial portion 26 to form the firstportion 12 comprising the cured elastomer with the plurality ofparticles 30 therein, and melting the plurality of particles 30 therebyforming the plurality of engagement voids 20 in the first portion 12comprising cured elastomer. In such embodiments, once melted, the moltenparticles 30 can be removed from the engagement voids 20gravimetrically, with an air knife, or in various other ways. In suchembodiments, the particles 30 are just as described above with diameter,amount used, etc. However, in these embodiments, the particles 30typically have a melting temperature of from about 100 to about 250,alternatively from about 125 to about 225, ° C. In this embodiment, theelastomeric composition can be cured (e.g. at a temperature as set forthin the temperature ranges above) and the elastomeric composition can befoamed simultaneously. That is, in various embodiments of this method,the steps of curing and foaming are conducted simultaneously. In suchembodiments, the melting and cure temperatures can be selected so thattwo steps can be completed simultaneously in an efficient process. Forexample, in one non-limiting embodiment, the particles 30 can comprise acrystalline wax which melts and flows out of the engagement voids 20during the step of curing. For example, in another non-limitingembodiment, the particles 30 can comprise a thermoplastic (e.g.polypropylene or polyethylene) which melts and flows out of theengagement voids 20 during the step of curing. The particles should meltover the range of curing temperatures of the uncured elastomer (e.g. ata temperature greater than 130° C.).

In other alternative embodiments, the step of forming a plurality ofengagement voids 20 comprises the steps of foaming a surface 28 of aninitial portion 26 comprising uncured elastomer, curing the initialportion 26 to form the plurality of engagement voids 20 in the firstportion 12 comprising cured elastomer. In this embodiment, theelastomeric composition can be cured (e.g. at a temperature as set forthin the temperature ranges above) and the blowing agent can be foamedsimultaneously. That is, in various embodiments of this method, thesteps of curing and foaming are conducted simultaneously. In suchembodiments, the curing and foaming (decomposition) temperatures can beselected so that two steps can be completed simultaneously in anefficient process.

In some such embodiments where the surface 28 of the initial portion 26is foamed, a chemical blowing agent can be included in the elastomericcomposition. The blowing agent can be dispersed throughout the initialportion 26 or concentrated near the surface 28 of the initial portion26. In some such embodiments, the elastomeric composition includes achemical blowing agent selected from the group of azo compounds, nitrosocompounds, hydrazines, hydrazine derivatives, hydrogen carbonates, andcombinations thereof. Specific non-limiting examples of such chemicalblowing agents include, but are not limited to, azodicarbonamide (ADCA),N,N-dinitroso pentamethylene tetramine (DPT), 4. 4′-oxybisbenzenesulfonyl hydrazide (OBSH), hydrazo dicarbonamide (HDCA), andsodium hydrogen carbonate (NaHCO₃). In some such embodiments, thechemical blowing agent is included in the elastomeric composition in anamount of from about 0.1 to about 50, alternatively from about 0.1 toabout 25, alternatively from about 0.1 to about 10, alternatively fromabout 1 to about 25, alternatively from about 1 to about 20,alternatively from about 1 to about 10, alternatively from about 1 toabout 5, alternatively from about 1 to about 7, alternatively from about5 to about 15, alternatively from about 5 to about 10, parts by weightbased on 100 parts by weight of the elastomeric composition.

In other alternative embodiments, the step of forming the plurality ofengagement voids 20 comprises the steps of pressing a patterned moldinto a surface 28 of an initial portion 26 comprising uncured elastomer,curing the initial portion 26 thereby forming the first portion 12comprising the cured elastomer with the patterned mold thereon, removingthe patterned mold to form the plurality of engagement voids 20 in thefirst portion 12 comprising cured elastomer.

The composite article 10 of the subject disclosure exhibits excellentadhesive properties—even at higher temperatures. In some embodiments,the composite article 10 has peel strength at least 2 times,alternatively 3 times, alternatively 4 times, alternatively 5 times,alternatively 6 times, alternatively 7 times, alternatively 8 times,alternatively 9 times, greater than the peel strength of a comparativecomposite article formed without a plurality of engagement voids butotherwise with the same process, when the testing is conducted at roomtemperature and in accordance with the T-peel test of ASTM D-1876 at acrosshead speed of 10 in/min. In some embodiments, the composite article10 has peel strength at least 2 times, alternatively 3 times,alternatively 4 times, alternatively 5 times, alternatively 6 times,alternatively 7 times, greater than the peel strength of a comparativecomposite article formed without a plurality of engagement voids butotherwise with the same process, when the testing is conducted at 80° C.and in accordance with the T-peel test of ASTM D-1876 at a crossheadspeed of 10 in/min.

In various embodiments, as part of the composite article 10, thecomposite article 10 can comprise more than two portions. If thecomposite article 10 includes more than two portions, at least two ofthe portions should be as described above. Composite articles of suchconfigurations can be part of a larger whole, e.g. integrated into aproduct such as a tire, a raft, or food packaging.

The following examples are intended to illustrate the instant disclosureand are not to be viewed in any way as limiting to the scope of theinstant disclosure.

EXAMPLES

The composite article of Example 1 is in accordance with the subjectdisclosure. The composite articles of Comparative Examples 1-3 are forcomparative purposes.

To form Example 1, a surface of a 4×4×0.1 inch initial portion of SBR 1is coated with a thin layer of NaCl particles (1.3 g/in²) having anaverage particle size of about 200 microns. SBR 1 is an elastomericcomposition comprising SBR, sulfur-based curatives, and additionaladditives. The samples were then pressed with 13 kN force for 30 minutesat 200° C. using a Carver press to cure the initial portion and form afirst portion presenting an engagement surface.

The first portion was soaked for 16 hours in water, which dissolves theNaCl particles to provide a first portion presenting with the engagementsurface having a plurality of engagement voids therein. Each engagementvoid penetrates into the engagement surface of the first portion and isdefined by a side wall which forms an acute angle with the engagementsurface. Each engagement void penetrates into the engagement surface ofthe first portion and is defined by a side wall which forms an acuteangle with the engagement surface. Of course, not all of the voidsformed in the engagement surface are engagement voids, i.e., not all ofthe voids formed form an acute angle with the engagement surface.

Once the first portion is formed, it is placed on an adjustable mold,with masking tape applied to one end of the engagement surface forpurposes of peel testing. The adjustable mold is set to a thickness of 6mm. A thermoplastic polyurethane (“TPU 1”) is injectionmolded/overmolded onto the engagement surface to form Example 1, acomposite article comprising a first portion comprising cured rubber,and a second portion comprising TPU 1. A locking surface of the secondportion of the composite article abuts the engagement surface anddefines a plurality of locking protrusions disposed in the plurality ofengagement voids of the first portion of the composite article. Example1 is molded on a Cincinnati Milacron Injection Molding Vista 110-10,equipped with a 40 mm general purpose screw design and a L/D of 16/1held within 3 barrels and a nozzle. The mold temperature is 30° C., thenozzle temperature is 210° C., and the sprue temperature is 215° C.during injection molding of the composite article. Example 1 is postcured for 20 hours at 100° C. This procedure is repeated 3 times toyield 3 samples of the composite article of Example 1.

TPU 1 is a polyester based TPU having the following physical properties:

-   -   Specific Gravity 1.21 g/cm³ (ASTM D 792);    -   Shore Hardness 95 A (ASTM D 2240 Shore A or D);    -   Taber Abrasion 30 mg loss (ASTM D 1044);    -   DIN Abrasion 25 mm³ loss (DIN 53516);    -   E-Modulus 9,000 PSI (ASTM D 412);    -   Flexural Modulus 11,000 PSI (ASTM D 790);    -   Tensile Strength 6,700 PSI (ASTM D 412);    -   Tensile Stress at 100% Elongation 2,200 PSI (ASTM D 412);    -   Tensile Stress at 300% Elongation 5,300 PSI (ASTM D 412);    -   Ultimate Elongation 440% (ASTM D 412);    -   Tear Strength 870 lb/in (ASTM D 624, Die C);    -   Compression Set 45% 22 h at 70° C. and 30% 22 h at 23° C. (ASTM        D 395 “B”, % of original);    -   Glass Transition temperature* −36° C.;    -   Vicat Softening Temperature 135° C. (ASTM D 1525); and    -   DMA Softening Temperature* 123° C.        -   Measured with Dynamic Mechanical Analysis (DMA).

A 1-inch wide strip is cut from each sample. Adhesion is measured usinga T-peel test in accordance with ASTM D-1876 at a crosshead speed of 10in/min. Peel testing is also conducted on Comparative Example 1, whichis a composite article formed with the same materials as example 1, butwith no engagement voids formed thereon. Peel testing is also conductedon Comparative Example 2, which is formed in accordance with theprocedure above, but with a cured initial portion. Likewise, peeltesting is conducted on Comparative Example 3, which is formed inaccordance with the procedure above, but the salt is dissolved beforethe initial portion is cured. Peel testing results are set forth inTable 1 below, with the number shown being an average of three.

TABLE 1 Peel Strength (lbs/in) Comparative Example 1 0.4 ComparativeExample 2 0.7 Comparative Example 3 0.5 Example 1 9.0

Referring now to Table 1 above, Example 1 exhibits superior peelstrength over Comparative Examples 1-3. The step of curing the firstportion with the NaCl particle therein is required and increases thepeel strength by about 18 times.

The composite article of Example 2 is in accordance with the subjectdisclosure. The composite articles of Comparative Examples 4 and 5 arefor comparative purposes.

To form Example 2, a surface of a 4×4×0.1 inch initial portion of SBR 2is coated with a thin layer of NaCl particles (1.3 g/in²) having anaverage particle size of about 200 microns. SBR 1 is an elastomericcomposition comprising SBR, sulfur-based curatives, and additionaladditives. The samples were then pressed with 5 kN force for 2 hours at149° C. using a Carver press to cure the initial portion and form afirst portion presenting an engagement surface.

The first portion was soaked for 16 hours in water, which dissolves theNaCl particles to provide a first portion presenting with the engagementsurface having a plurality of engagement voids therein. Each engagementvoid penetrates into the engagement surface of the first portion and isdefined by a side wall which forms an acute angle with the engagementsurface. Each engagement void penetrates into the engagement surface ofthe first portion and is defined by a side wall which forms an acuteangle with the engagement surface. Of course, not all of the voidsformed in the engagement surface are engagement voids, i.e., not all ofthe voids formed form an acute angle with the engagement surface.

Once the first portion is formed, it is placed on an adjustable mold,with masking tape applied to one end of the engagement surface forpurposes of peel testing. The adjustable mold is set to a thickness of 6mm. A thermoplastic polyurethane (“TPU 2”) is injectionmolded/overmolded onto the engagement surface to form Example 2, acomposite article comprising a first portion comprising cured rubber,and a second portion comprising TPU 2. A locking surface of the secondportion of the composite article abuts the engagement surface anddefines a plurality of locking protrusions disposed in the plurality ofengagement voids of the first portion of the composite article. Example2 is molded on a Cincinnati Milacron Injection Molding Vista 110-10,equipped with a 40 mm general purpose screw design and a L/D of 16/1held within 3 barrels and a nozzle. The mold temperature is 30° C., thenozzle temperature is 210° C., and the sprue temperature is 215° C.during injection molding of the composite article. Example 2 is postcured for 20 hours at 50° C. This procedure is repeated 3 times to yield3 samples of the composite article of Example 2.

TPU 1 is a polyether based TPU having the following physical properties:

-   -   Specific Gravity 1.13 g/cm³ (ASTM D 792);    -   Shore Hardness 90 A (ASTM D 2240 Shore A or D);    -   Taber Abrasion 45 mg loss (ASTM D 1044);    -   DIN Abrasion 25 mm³ loss (DIN 53516);    -   E-Modulus 4,500 PSI (ASTM D 412);    -   Flexural Modulus 4,200 PSI (ASTM D 790);    -   Tensile Strength 5,400 PSI (ASTM D 412);    -   Tensile Stress at 100% Elongation 1,800 PSI (ASTM D 412);    -   Tensile Stress at 300% Elongation 4,000 PSI (ASTM D 412);    -   Ultimate Elongation 460% (ASTM D 412);    -   Tear Strength 730 lb/in (ASTM D 624, Die C);    -   Compression Set 45% 22 h at 70° C. and 25% 22 h at 23° C. (ASTM        D 395 “B”, % of original);    -   Glass Transition temperature* −35° C.;    -   Vicat Softening Temperature 120° C. (ASTM D 1525); and    -   DMA Softening Temperature* 100° C.        -   *Measured with Dynamic Mechanical Analysis (DMA).

A 1-inch wide strip is cut from each sample. Adhesion is measured usinga T-peel test in accordance with ASTM D-1876 at a crosshead speed of 10in/min. Peel testing is also conducted on Comparative Example 4, whichis a composite article formed with the same materials as Example 1, butwith no engagement voids formed thereon. Peel testing is also conductedon Comparative Example 5, which is formed in accordance with theprocedure above, but with a cured initial portion. Peel testing resultsare set forth in Table 2 below, with the number shown being an averageof three.

TABLE 2 Peel Strength at Room Peel Strength at 80° C. Temperature(lbs/in) (lbs/in) Comparative Example 4 1.96 0.806 Comparative Example 52.212 0.733 Example 2 6.918 1.59

Referring now to Table 2 above, Example 2 exhibits superior peelstrength over Comparative Examples 4 and 5. The step of curing the firstportion with the NaCl particle therein is required and increases thepeel strength by 3 times. At high temperature (80° C.), a condition atwhich adhesion is particularly difficult to achieve, Example 2 exhibitsabout 2 times the peel strength of Comparative Examples 4 and 5.

It is to be understood that the appended claims are not limited toexpress any particular compounds, compositions, or methods described inthe detailed description, which may vary between particular embodimentswhich fall within the scope of the appended claims. With respect to anyMarkush groups relied upon herein for describing particular features oraspects of various embodiments, it is to be appreciated that different,special, and/or unexpected results may be obtained from each member ofthe respective Markush group independent from all other Markush members.Each member of a Markush group may be relied upon individually and or incombination and provides adequate support for specific embodimentswithin the scope of the appended claims.

It is also to be understood that any ranges and subranges relied upon indescribing various embodiments of the present invention independentlyand collectively fall within the scope of the appended claims, and areunderstood to describe and contemplate all ranges including whole and/orfractional values therein, even if such values are not expressly writtenherein. One of skill in the art readily recognizes that the enumeratedranges and subranges sufficiently describe and enable variousembodiments of the present disclosure, and such ranges and subranges maybe further delineated into relevant halves, thirds, quarters, fifths,and so on. As just one example, a range “of from 0.1 to 0.9” may befurther delineated into a lower third, i.e., from 0.1 to 0.3, a middlethird, i.e., from 0.4 to 0.6, and an upper third, i.e., from 0.7 to 0.9,which individually and collectively are within the scope of the appendedclaims, and may be relied upon individually and/or collectively andprovide adequate support for specific embodiments within the scope ofthe appended claims. In addition, with respect to the language whichdefines or modifies a range, such as “at least,” “greater than,” “lessthan,” “no more than,” and the like, it is to be understood that suchlanguage includes subranges and/or an upper or lower limit. As anotherexample, a range of “at least 10” inherently includes a subrange of fromat least 10 to 35, a subrange of from at least 10 to 25, a subrange offrom 25 to 35, and so on, and each subrange may be relied uponindividually and/or collectively and provides adequate support forspecific embodiments within the scope of the appended claims. Finally,an individual number within a disclosed range may be relied upon andprovides adequate support for specific embodiments within the scope ofthe appended claims. For example, a range “of from 1 to 9” includesvarious individual integers, such as 3, as well as individual numbersincluding a decimal point (or fraction), such as 4.1, which may berelied upon and provide adequate support for specific embodiments withinthe scope of the appended claims.

The present disclosure has been described in an illustrative manner, andit is to be understood that the terminology which has been used isintended to be in the nature of words of description rather than oflimitation. Obviously, many modifications and variations of the presentdisclosure are possible in light of the above teachings. It is,therefore, to be understood that within the scope of the appendedclaims, the present disclosure may be practiced otherwise than asspecifically described.

1. A method of forming a composite article including a first portioncomprising a cured elastomer and presenting an engagement surface, and asecond portion comprising a thermoplastic composition and presenting alocking surface, said method comprising the steps of: forming aplurality of engagement voids in the first portion wherein eachengagement void penetrates into the engagement surface of the firstportion and is defined by a side wall which forms an acute angle withthe engagement surface; and applying the thermoplastic composition ontothe engagement surface of the first portion to form the second portionsuch that the locking surface abuts the engagement surface and defines aplurality of locking protrusions disposed in the plurality of engagementvoids of the first portion.
 2. A method as set forth in claim 1 whereinthe step of forming the plurality of engagement voids comprises thesteps of: pressing a plurality of particles into a surface of an initialportion comprising uncured elastomer; curing the initial portion to formthe first portion comprising the cured elastomer with the plurality ofparticles pressed therein; and dissolving the plurality of particles ina solvent thereby forming the plurality of engagement voids in the firstportion comprising cured elastomer.
 3. A method as set forth in claim 2wherein the plurality of particles have an average diameter of fromabout 10 to about 500 mm.
 4. A method as set forth in claim 2 whereinthe plurality of particles has a solubility of greater than about 1 gper 100 mL of the solvent at standard temperature and pressure.
 5. Amethod as set forth in claim 2 wherein the solvent is a polar solvent.6. A method as set forth in claim 2 wherein the particles comprise asalt selected from the group of nitrates, sulfates, chlorides, bromides,iodides, sodium carbonate, potassium carbonate, ammonium carbonate,sodium hydroxide, potassium hydroxide, and ammonium hydroxide.
 7. Amethod as set forth in claim 2 wherein the particles comprise sodiumchloride.
 8. A method as set forth in claim 2 wherein the solventcomprises water.
 9. A method as set forth in claim 1 wherein the step offorming the plurality of engagement voids comprises the steps of:pressing a plurality of particles into a surface of an initial portioncomprising uncured elastomer; curing the initial portion to form thefirst portion comprising the cured elastomer with the plurality ofparticles therein; and melting the plurality of particles in a solventthereby forming the plurality of engagement voids in the first portioncomprising cured elastomer.
 10. A method as set forth in claim 9 whereinthe plurality of particles have an average diameter of from about 10 toabout 500 mm.
 11. A method as set forth in claim 9 wherein the pluralityof particles have a melting temperature of from about 100 to about 250°C.
 12. A method as set forth in claim 9 wherein the steps of curing andmelting are conducted simultaneously.
 13. A method as set forth in claim1 wherein the step of forming the plurality of engagement voidscomprises the steps of: pressing a patterned mold into a surface of aninitial portion comprising uncured elastomer; curing the initial portionthereby forming the first portion comprising the cured elastomer withthe patterned mold thereon; removing the patterned mold to form theplurality of engagement voids in the first portion comprising curedelastomer.
 14. A method as set forth in claim 1 wherein the step offorming a plurality of engagement voids comprises the steps of: foaminga surface of an initial portion comprising uncured elastomer; curing theinitial portion to form the plurality of engagement voids in the firstportion comprising cured elastomer.
 15. A method as set forth in claim14 wherein the steps of foaming and curing are conducted simultaneously.16. A method as set forth in claim 1 further comprising the step ofpre-treating the engagement surface of the first portion with anadhesion promoter.
 17. A method as set forth in claim 1 wherein the stepof applying the thermoplastic composition onto the engagement surface ofthe first portion is conducted via injection molding.
 18. A method asset forth in claim 1 wherein the cured elastomer comprises an elastomerselected from natural polyisoprene, synthetic polyisoprene,polybutadiene, chloroprene rubber, butyl rubber, halogenated butylrubber, styrene-butadiene rubber, nitrile rubber, ethylene propylenerubber, ethylene propylene diene rubber, epichlorohydrin rubber,polyacrylic rubber, silicone rubber, fluorosilicone rubber,fluoroelastomers, perfluoroelastomers, polyether block amides,chlorosulfonated polyethylene, and ethylene-vinyl acetate. 19.(canceled)
 20. A method as set forth in claim 1 wherein thethermoplastic composition comprises a thermoplastic elastomer selectedfrom polyethylene, polypropylene, polyamide, or thermoplasticpolyurethane.
 21. A method as set forth in claim 1 wherein the firstportion also defmes a plurality of voids that are different than theplurality of engagement voids, wherein each void defmes an opening inthe engagement surface, penetrates into the first portion, and isdefined by a side wall which does not form an acute angle with theengagement surface, and wherein the second portion defmes a plurality ofprotrusions disposed in the plurality of voids.
 22. (canceled) 23.(canceled)
 24. (canceled)